1. Field of the Invention
The present invention relates to a sport boot for performing a gliding sport, such as cross-country skiing, namely, performing skating steps (or skating), of a type including an outer sole and a lower shank, provided by a heel cap on which a rigid collar is hinged which is designed to surround the lower leg and which extends towards the top of the shank starting from the hinge beyond the upper end thereof.
2. Discussion of Background and Relevant Information
In the course of performing cross-country skiing, after the skier has ended his or her forward movement on one of the skis, the skier transfers his or her weight to the other, opposite ski, and advances the first ski to the level of the second.
This advancement differs depending on:
--the speed (hence the step used). Actually, the slower the speed, the more the frequency of gliding is increased and therefore the less time the skier has for bringing the ski forward. This is because the slower the speed, the less the skis are advanced parallel, and the more does the skier keep a considerable distance between the two skis. PA1 --the encountered slope. Actually, the skier ought to advance the ski in as parallel a manner as possible for contact with the slope so that he or she does not lift the ski too high. Thus the inclination of the ski while being advanced depends on the encountered slope (which makes advancing it particularly hard and difficult on strong inclines).
These different statements have led to a study of the problem of advancing skis during the performance of skating.
This study has in fact shown that at the time of the disengagement of the ski, its front end or spatula catches on the snow, which causes the very problem residing in the angular longitudinal control of the ski in a quasi-static phase, i.e., in the air. The same problem is posed in other gliding sports, such as ice-skating, in-line skating, where the sportsman must avoid striking the ground with the gliding device (skate . . . ) during the phase of advancing it.
With the problem thus posed, it has also been stated that this results in a consistent consequence for the skier, namely to have to increase the contraction of the anterior tibia for picking up the ski again and to prevent the spatula from catching on the snow during the phase when the ski is advanced. This is all the more unfortunate for the skier because the skier should instead take advantage of this phase for relaxing the muscles of the affected leg to the maximum, because this is the occurrence of a rest and non-moving period.
Applicant had already remedied these disadvantages based on the posed problem, by proposing in French Patent Publication No. 2,676,624 a boot of the previously mentioned type, which is equipped with energizing means for the angular longitudinal control of a ski with the air in respect to the sole of the boot during the phase of advancing the ski.
Such means actually consist in a movement energy between the hinged collar and the shank, advantageously offering an effective assistance for the tibia during this phase of performing skating.
It also results in reduced fatigue for the skier which saves his or her muscles.
Thanks also to these means, the feeling of heaviness of the ski in the area of the spatula is noticeably reduced, and they assure a better anterior-posterior posture as well as a much easier advancement of the ski. Then the start-over takes place under the best conditions because the fatigue is less.
However, the tests have made it also possible to state that although the energizing means have provided a certain assistance in the advancement phase, this has been offset by the generation of fatigue, formerly non-existent, during the pushing phase, more particularly during the forward flexing of the leg in connection with the foot, because actually the collar and the shank are always connected. In fact, during the aforementioned position, it is desirable that the foot should be advantageously free, instead of having to overcome a useless force at that moment, which was precisely provided by the permanent energizing means.